In a letter to the Treasury Department’s General Counsel Brent McIntosh, Trump attorney William Consovoy wrote that Neal was wrong in asserting that Treasury can’t “question or second-guess” Congress’s motives.

Neal, in his original request to the Treasury Department and in a follow-up letter on Saturday, asked for six years of Trump’s personal and business returns and related documents.

The Massachusetts Democrat wrote that the legislative purpose in requesting the returns is so that Congress can ensure the Internal Revenue Service is following its stated policy of auditing the president and vice president.

"No one actually believes this,” Consovoy wrote of Neal’s stated motive. Instead, the attorney characterized the request as a political attack because Neal is only seeking returns for Trump, including years that predate Trump’s election.

“Chairman Neal’s request is nothing more than an attempt to exercise constitutional authority that Congress does not possess,” Consovoy wrote.

In response to Neal’s first letter on April 3, Treasury Secretary Steven Mnuchin wrote that the department would wait to get a legal opinion from the Department of Justice before responding. Neal’s response on Saturday gave a new deadline of April 23 before his committee would potentially resort to other legal options.

To contact the reporter on this story: Joe Light in Washington at jlight8@bloomberg.net

To contact the editors responsible for this story: Wendy Benjaminson at wbenjaminson@bloomberg.net, Anna Edgerton